Somehow, the Do Not Disturb function is staying on, even when people thought they had programmed it only for a certain period of time. (For those who don't already know, Do Not Disturb is a feature that users are supposed to be able to switch on to silence in-coming calls, alerts, and notifications, or set up to perform such silencing during a preordained period of time.)

Apple admits that this is affecting not merely some users of the iPhone but also of the iPad and the iPod Touch.

The notice explains: "Do Not Disturb scheduling feature will resume normal functionality after January 7, 2013. Before this date, you should manually turn the Do Not Disturb feature on or off."

To do this you must "tap Settings > Notifications > Do Not Disturb and switch Scheduled to Off."

There is no explanation as to why it will take Apple another few days to fix the problem.

Perhaps there are more Apple employees than usual on vacation at this time and they've all got their Do Not Disturb malfunctioning on their iPhones.